Another useful tip for break in, would be to pretty much ignore your manufacturer's engine break in instructions, and go with the heat cycle method, sometimes called the Bess method.
Manufacturer's break in methods suggest that you run the car as rich as possible for several tanks, before finally leaning out the engine gradually. Many believe this is bad and prefer instead the heat cycle method for two reasons:
1. By running your engine excessively rich, you are putting undue stress on the internal components such as connecting rods, and crankshafts since the engine is almost hydro-locking (flooding) by their recommendations.
2. By running the engine excessively rich, you are keeping the temperatures too low to allow for proper metal expansion of the sleeve. This can cause premature wear, since the tapered portion of the sleeve will remain overly tight in a rich (and cool) state.
Pick up a temperature gauge such as OFNA's PCR gauge (only $30.00), you cannot imagine how much easier this will make engine tuning.
This method involves running your kit at temperatures above 200, but below 250 degrees (measured at glow plug) for 2-3 minute intervals. Making sure smoke is visible for low to mid RPMs when accelerating. Keep below half throttle, and don't make too sudden of throttle inputs. After that, shut the car down and move the piston to bottom dead center (BDC) in the stroke**. Allow the car to cool fully to ambient air temperature, and then repeat this process, for about a half hour worth of driving time (not including cool down time).
** Before you run the car the first time, mark BDC by removing your glow plug, and inserting a thin object, such as a flat blade screwdriver, or antenna tube to rest on top of the piston. Rotate the flywheel until the object is at its lowest point. Mark this with a scratch on your flywheel so that you can orient the motor to this position quickly each time you shut your car off (for the life of the engine, not just break in). This is because these model engines do not have ring seals like a normal piston. They use a tapered cylinder to create a seal. By lowering your piston below the "pinch" after each run, you will prolong engine life by preserving this sealing effect.
NOTE:
Leaner = Clockwise
Richer = Counter-clockwise
Temperatures are typically reduced by making the engine richer, and vice versa
Once you have completed the break in method above, follow the below steps to fine tune your engine.
- Set your needles to their default postions (including your idle).
- Run the car until it is warmed up. If you are having trouble getting it started, try leaning the high speed needle 1/12th of a turn (one hour on a clock) leaner until the engine starts. Keep an eye on temperatures making sure they don't exceed 250 degrees.
- Gradually lean the high speed needle until your temperatures reach 220-250 degrees. Make sure you smoke is visible from the exhaust when accelerating between low to mid RPMs.
- Once the high speed needle is in range, bring the car in, and pinch the fuel line until the engine stalls. It should take between 3-5 seconds for this to happen. If it takes less richen the low speed needle 1/12th of a turn. If it takes more lean the lean the low speed needle 1/12th of a turn. Keep an eye on temperatures to make sure you are still within range, as adjusting the low speed needle can sometimes have an effect on temperature.
- Once your high and low speed needles are properly adjusted, adjust your idle so that it is as high as it can be without the car moving. You will note that changes to the other needles will have an effect on your idle.
- Repeat this process (except the first step) any time the weather changes while driving (overcast, windy, etc) and at the beginning of a day of driving.
If you notice an excessive fluctuation between full tank and close to (but not all the way) empty tank temperatures try the following:
1. Purchase a fuel filter
2. Remove the inner filter element
3. Install the fuel filter on your pressure line (the line running between the top of the gas tank and the exhaust pipe)
This keeps overflow from a full tank from clogging your pressure line, by giving it a place to collect. By keeping your pressure line clear, this helps ensure that the motor won't lean bog from lack of tank pressure when you fill up.
